ONAGAWA, Miyagi Pref. — The International Atomic Energy Agency started an inspection Monday in Miyagi Prefecture of the Onagawa nuclear plant, which was relatively undamaged by the massive earthquake and tsunami that hit the area in March last year.

A 20-member delegation led by Sujit Samaddar, head of the IAEA’s International Seismic Safety Center, will check on damage to facilities and equipment at the Tohoku Electric Power Co. plant, whose three reactors automatically shut down when the disaster struck.

During its inspection through Aug. 11, the IAEA team will also analyze the plant’s operational data and interview workers about how they stabilized the reactors so the agency can share its findings with member countries and help them compile safety measures.

The IAEA has already conducted on-site investigations at Tokyo Electric Power Co.’s crisis-hit Fukushima No. 1 and nearby Fukushima No. 2 plants in Fukushima Prefecture and on Japan Atomic Power Co.’s Tokai No. 2 plant in Ibaraki Prefecture since the March 2011 disaster.

While the IAEA’s inspections have focused on nuclear power plants in eastern regions, the west also poses several reasons for concern. The experimental Monju prototype fast-breeder reactor in Tsuruga, Fukui Prefecture, is one of them.

Monju’s operator, Japan Atomic Energy Agency, said an alarm early Monday indicated that sodium coolant was leaking. No leak or environmental contamination was detected, it said.

The Monju project started as part of the government program to establish a perpetual nuclear fuel cycle, in which spent fuel from power plants is reprocessed for use as plutonium-uranium mixed-oxide fuel, or MOX.

But the program was hobbled by problems. Monju has not effectively been operational since it was damaged by a sodium coolant leak and fire in 1995, after which the operator tried to cover up the damage.

The government has been considering four options on Monju’s fate — ranging from decommissioning to going ahead with the fuel cycle program.